THE ARGUMENT 263 



that light readily penetrates it to considerable 

 depths. As for color, landscape and modern 

 chemical industry alike testify to the availa- 

 bility of carbon compounds as its source. 



A final test of thoroughness may be based 

 upon a consideration of other compounds 

 and elements. Accepting the decision that 

 no other properties can be so important to 

 an active, complex, and regulated mechan- 

 ism as those possessed nearly or quite as 

 maxima by water, carbonic acid, and the 

 compounds of the three elements, what are 

 the possibilities of obtaining the same char- 

 acteristics from other substances ? 



So far as chemical substances are now 

 known, the only compound which can be even 

 considered on this score as a substitute for 

 water in the environment is ammonia, and 

 in many respects, no doubt, ammonia might 

 serve as well. 1 However, chemical processes 



1 A full discussion of the properties of ammonia which qual- 

 ify it as a substitute for water in the role of solvent and other- 

 wise will be found in the article by E. C. Franklin, "The 

 Ammonia System of Acids, Bases, and Salts," American Chem- 

 ical Journal, Vol. 47, p. 285, 1912. In this paper the re- 

 sults of a long series of investigations are brought together. 

 Especially important for the present purpose are the intro- 

 ductory remarks. 'The many striking analogies between 

 liquid ammonia and water as electrolytic solvents have been 

 emphasized by the writer and his co-workers in papers which 

 have appeared from time to time during the past decade. In 



